1. Field of the Invention
The present invention relates to an ultrasonic transducer. More specifically, the present invention relates to an ultrasonic transducer which is a device functioning as a source for projecting an ultrasonic wave to a sample to be examined and functioning as a source for receiving a wave reflected from the sample.
2. Description of the Background Art
An ultrasonic inspection apparatus is known as an apparatus which projects an ultrasonic wave to a sample to be examined, dipped in water, through the water, receives a reflected wave from the sample and detects a defect such as a break away or a flaw in the sample based on a wave form of an echo signal of the reflected wave (for example, Japanese Utility Model Laid-Open 6-80169),
FIG. 12 shows an example of a conventional ultrasonic inspection apparatus. As shown in FIG. 12, the conventional ultrasonic inspection apparatus 100 comprises a water bath 11 filled with water W, a sample to be examined 12 provided to be dipped in water bath 11, an ultrasonic transducer 50 functioning as a source for projecting an ultrasonic wave to the sample to be examined 12 and functioning as a source for receiving a reflected wave from the sample 12, a transmitter/receiver circuit 16 sending a drive pulse to the ultrasonic transducer 50 and amplifying an echo signal received, an electric connecting cord 17 for electrically connecting between the ultrasonic transducer 50 and the transmitter/receiver circuit 16, a scanning device 13 for moving the ultrasonic transducer 50 in horizontal and vertical directions, a power source 14 for supplying power to the respective parts, and a determination device 15 for determining existence of defect in the sample 12 based on the wave form of the echo signal outputted from the transmitter/receiver circuit 16.
The ultrasonic wave projected from ultrasonic transducer 50 has a high-frequency component of from about 10 MHz to about 200 MHz. Further, the electric signal outputted from ultrasonic transducer 50 after receiving the reflected wave is a signal having a very low voltage of about several mV.
In such a conventional apparatus, the length of the electric connecting cord 17 for electrically connecting between the ultrasonic transducer 50 and the transmitter/receiver circuit 16 was several-tens cm at shortest, and in a case of a long cord, it was several meters. If the electric connecting cord 17 is thus long, when a drive pulse is sent from the transmitter/receiver circuit 16 to the ultrasonic transducer 50, there is a case where the drive pulse is attenuated and weakened. Similarly, when an echo signal is sent from the ultrasonic transducer 50 to the transmitter/receiver circuit 16, there is a case where the high-frequency component of the echo signal is attenuated and weakened. As a result, there occurs a problem that the examination accuracy may deteriorate. Recently, miniaturization of electronic parts is proceeded, and when such electronic parts are employed as the samples to be examined 12, it is an important subject to be able to detect very fine defects. Therefore, it is important to be able to send and receive high-frequency wave components having a high resolution without weakening.